The present invention is directed to bicycle brake devices and, more particularly, to bicycle brake devices that are used to brake a hub of a bicycle wheel.
Bicycle braking devices currently available include rim braking devices and hub braking devices. Rim braking devices include cantilever brakes or caliper brakes that brake the rim of the wheel. Hub braking devices brake the wheel hub, and they include drum brakes, band brakes, roller brakes and the like. A hub brake brakes the hub of the wheel, so it is able to provide braking even if the wheel rim is warped.
A drum brake such as a roller brake effects braking by means of friction created when a brake shoe contacts the inside peripheral face of a tubular brake drum that rotates in unison with the wheel hub. A band brake effects braking by means of friction created when a brake belt contacts the outer peripheral face of a brake drum. In a roller brake, rollers spaced apart in the circumferential direction are displaced diametrically outward by a cam in order to move a brake shoe against the inner peripheral face of the brake drum. Grease is injected into the interior of the brake drum to ensure smooth displacement of the rollers.
In brake devices of this kind, there is provided a brake actuator having an actuator arm for moving the brake shoe or brake band into contact with the brake drum, wherein the brake arm is rotatably mounted at its basal end to a fastening bracket. The inner cable of a Bowden brake cable is attached to the distal end of the actuating arm so that the actuating arm may be rotated by pulling and releasing the inner cable relative to the outer cable of the Bowden cable that is attached to the bicycle frame or to the fastening bracket.
Since this kind of brake device is linked to the wheel hub, the brake device ordinarily is detached together with the wheel when the wheel is detached from the frame. It is usually necessary to detach the inner cable from the actuating arm when so detaching the wheel. Accordingly, it is desirable that the inner cable be readily detachable from the actuating arm, especially when a quick release mechanism is used to attach the wheel to the frame. When the outer cable is detained by an outer mounting portion disposed on a fastening bracket, it will be necessary to detach the outer cable as well.
In a conventional inner cable retaining structure, the end of the inner cable is attached by a screw to an inner detaining portion, wherein the inner detaining portion is detachably attached to an inner mounting portion that is rotatably linked to the actuating arm. Thus, the inner cable may be detached by detaching the inner detaining portion from the inner mounting portion. More specifically, the inner mounting portion typically has a plate-shaped mounting body that is rotatably attached to the actuating arm. The inner detaining portion comprises a detaining body having a shaft configuration and an inner fastening portion for screwing the inner cable to the detaining body. The mounting body has formed therein a detaining slot and a circular detachment slot. The detaining slot has, for example, two parallel faces for detaining the detaining body, and the detaining body has formed therein a slit having two mutually parallel faces that engage the detaining slot so that the detaining body may be detained by the detaining slot. The detachment slot is situated adjacent to the detaining slot and has a size that allows the detaining body to pass through it. The inner mounting portion has a resilient member surrounding the detaining slot to retain the detaining body in place in the detaining slot. In contrast to designs in which the inner cable itself is removed from the inner detaining portion, this arrangement does not require adjusting the play of the brake each time it is detached, thus facilitating detachment of the inner cable.
The procedure for attaching the inner cable involves first swinging the actuating arm towards the braking position. Next, with the inner cable screwed to the inner fastening portion, the detaining body is inserted into the detaining slot. With the slit of the detaining body mated with the detaining slot, the inner detaining portion is attached to the inner mounting portion. To detach the inner cable, the actuating arm is again swung towards the braking position so that the inner cable is loosened, and the inner detaining portion is detached from the inner mounting portion by performing the preceding operation in reverse.
In a conventional structure where the outer cable is detained by an outer mounting portion that is disposed on a fastening bracket, the outer mounting portion is designed to be detachable from an outer fastening slot that is also formed with the fastening bracket. More specifically, the outer mounting portion comprises a rod-shaped tubular outer detaining portion with a threaded outer peripheral surface, and an outer fastening portion with a threaded hole. The outer detaining portion detains the outer cable, and the outer detaining portion and the outer fastening portion are screwed together in such a way that the detained position of the outer detaining portion may be adjusted in the direction of the cable axis. An annular mounting recess is formed on one end of the outer fastening portion, wherein the mounting recess catches in the outer fastening slot to detachably lock the outer mounting portion to the fastening bracket. It is therefore easy to detach the outer cable when detaching the wheel.
When attaching the outer cable, the inner cable is inserted through the outer detaining portion, and the outer detaining portion detains the end of the outer cable. Then, the outer fastening portion is grasped and attached to the fastening bracket by engaging the mounting recess with the fastening slot. To remove the outer mounting portion, the outer fastening portion is grasped and removed from the outer fastening slot.
With the designs described above, the inner cable attachment or detachment procedure is performed with the actuating arm manually swung towards the braking position. Accordingly, one hand must be used to turn the actuating arm. The actual inner cable attachment or detachment procedure therefore must be performed with the remaining hand. Since the inner detaining portion is a small, shaft-shaped member, and a resilient member holds the detaining body in place on the mounting body, it is sometimes difficult to grasp the detaining body in order to disengage it from the detaining slot or engage it within the detaining slot. In some instances, the tip of a screwdriver or other tool must be used to push the inner detaining portion in order to attach or detach it.
Furthermore, the outer mounting portion is also a small, shaft-shaped member. As a result, the outer mounting portion also is difficult to grasp, and the attachment/detachment operation is fairly difficult to perform. Additionally, the outer mounting portion is detachably detained and fastened by means of the mounting recess and the outer fastening slit, which makes it impossible to securely fasten the outer cable. As a result, in some instances the outer detaining portion may twist during the braking operation. Twisting of the outer detaining portion creates the perception of an increase in brake play and may adversely affect brake lever response.